Criticisms of Theory of Natural Selection. 371 



organ, even after it has attained its full development, 

 continues \\sgrowth with the growth of the fish, and 

 this in a much higher ratio, either than the tail alone, 

 or the whole animal. Lastly, Prof. Burdon Sanderson 

 finds that section for section the organ in the skate is 

 as efficient as it is in Torpedo. It is evident that 

 these facts also point to the skate's organ being in 

 course of phylogenetic evolution. 



Again, it cannot be answered that the principle 

 of correlation may be drawn upon in mitigation of 

 the difficulty. The structure of the electric organ 

 is far too elaborate, far too specialized, and far too 

 obviously directed to a particular end, to admit of our 

 conceivably supposing it due to any accidental corre- 

 lation with structural changes going on elsewhere. 

 Even as regards the initial changes of muscle-elements 

 into electrical-elements, I do not think the principle 

 of correlation can be reasonably adduced by way 

 of explanation ; for, as shown in the illustrations, 

 even this initial change is most extraordinarily 

 peculiar, elaborate, and specialized. But, be this as 

 it may, I am perfectly certain that the principle of 

 correlation cannot possibly be adduced to explain the 

 subsequent association of these electrical elements into 

 an electric battery, actuated by a special nervous me- 

 chanism of enormous size and elaboration unless, of 

 course, the progress of such a structure were assumed 

 to have been throughout of some utility. Under this 

 supposition, however, the principle of correlation would 

 be forsaken in favour of that of natural selection ; and 

 we should again be in the presence of the same diffi- 

 culty as that with which we started. 



But now, and further, if we do thus abandon corre- 

 B b 2 



